System for the electrically connecting at least one light source to an electrical power supply system

ABSTRACT

A system for electrically connecting at least one light source to a system for supplying electrical power, wherein the connecting system comprises a lead frame able to be electrically connected to a system for supplying electrical power, the lead frame including at least one connecting terminal and at least one connecting means allowing the connecting terminal of the lead frame to be electrically connected to the light source, the connecting terminal and the connecting means being able to electrically connect the light source to the lead frame, thereby allowing the light source to be placed away from the lead frame.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/594,465, filed Oct. 7, 2019, which is a continuation of U.S.application Ser. No. 15/027,309 filed Apr. 5, 2016, which is the U.S.National Phase application of PCT Application No. PCT/EP2014/072343filed Oct. 17, 2014, and claims priority to the French Application No.1360174 filed on Oct. 18, 2013. The entire contents of each of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The subject of the present invention is a system for electricallyconnecting at least one light source to a system for supplyingelectrical power.

It typically, but not exclusively, is applicable to a system allowing atleast one light emitting diode to be electrically connected to thesystem for supplying electrical power of a motorized vehicle.

2. Description of the Related Art

Patent application FR 2 906 347 discloses a vehicle light device thatcomprises a lighting module, this module including:

-   -   lighting devices each comprising a light-emitting unit;    -   a conductive board that includes cavities for receiving the        lighting devices, this board allowing the lighting devices to be        connected, especially by means of electrical tracks, to a source        of electrical power;    -   a heat-dissipating holder on which the lighting devices are        placed;    -   an adhesive part placed between the dissipating holder and the        conductive board, which especially allows the lighting devices        to be precisely positioned in the cavities of the conductive        board.

It turns out that the conductive board of the lighting module that isthe subject of patent application FR 2 906 347 must necessarily comprisethe cavities in order to be able to place the lighting devices therein.Additional forming operations must thus be carried out in order to givethe conductive board a specific shape.

In addition, in order to preserve the luminous efficacy of the lightingdevices, it is recommendable to make use of a system for dissipatingheat, such as the heat-dissipating holder, thereby complicating thestructure of the lighting module.

SUMMARY OF THE INVENTION

The objective of the present invention is especially to remedy thesedrawbacks by providing a system for electrically connecting at least onelight source such as a light-emitting diode to a system for supplyingelectrical power, the simplified structure of which especially allowsdesign and production costs to be decreased.

For this purpose, it provides a system for electrically connecting atleast one light source to a system for supplying electrical power,wherein the connecting system comprises:

-   -   a lead frame able to be electrically connected to a system for        supplying electrical power, the lead frame including at least        one connecting terminal; and    -   at least one connecting means allowing the connecting terminal        of the lead frame to be electrically connected to the light        source,

the connecting terminal and the connecting means being able toelectrically connect the light source to the lead frame, therebyallowing the light source to be placed away from the lead frame.

Above and in what follows, a lead frame is a structure of conductivetracks, which structure is of integral construction. This lead frame mayfor example be a plate stamped to form the electrical tracks, thenovermolded on an insulating substrate and the portions of which otherthan those forming the tracks are separated from the plate after theovermolding.

In this way, the light source is electrically connected to the leadframe while being remote and distant from the latter, therebyadvantageously allowing the structure of the lead frame to besimplified. Specifically, it is no longer necessary to make provisionfor a specific location in the lead frame in order to place therein thelight source or to fix to the lead frame a means for specificallydissipating the heat emitted by the light source. An arrangement of thelight source away from the lead frame is defined as being an arrangementof the light source at a distance from the lead frame that significantlydecreases or even prevents the exposure of the lead frame to the heatemitted by the light source, thereby making it possible to dispense withfastening the lead frame to a means able to specifically dissipate theheat of the light source.

Preferably, the lead frame includes a first means for dissipating heatallowing the heat generated by the lead frame to be dissipated.

Preferably, the first means for dissipating heat is a resistive circuit.

Preferably, the lead frame includes a converter allowing the, especiallyAC, voltage of the current delivered by the system for supplyingelectrical power to be converted into an, especially DC, voltage appliedto the connecting terminal of the lead frame.

The voltage applied to the connecting terminal is preferably suitablefor supplying the light source with power.

The lead frame may include a means for protecting from electromagneticinterference.

The first means for dissipating heat advantageously consists of theconverter. In this case, the converter is able to continue to operatenormally even in the case of substantial heat dissipation.

Advantageously, the lead frame includes a control circuit that controlsthe voltage of the current applied to the connecting terminal.

Preferably, the connecting terminal of the lead frame is a connectingpad able to allow the light source to be connected by application of thewire bonding technique. This connection may be achieved by a conductivebridge for example.

Preferably, the connecting means is an electrically conductive wire.

Preferably, the lead frame comprises a printed circuit board to whichelectronic components may be connected.

This board comprises a plurality of electrical tracks allowingelectrical current to be transported, electronic components beingsoldered to these tracks using connecting pins.

If needs be, the end of the connecting pins of the electronic componentspasses through through-holes in the board, thereby allowing visualinspection of the quality of the solder joints foimed on these ends tobe carried out by means of optical devices.

Preferably, the lead frame comprises an advantageously electricallyinsulating border extending perpendicularly from the board, this borderincluding:

-   -   two substantially parallel longitudinal walls; and    -   two substantially parallel transverse walls, which each connect        the two longitudinal walls.

The border and the board advantageously define a seal-tight tray, thistray being filled with a liquefied plastic product.

One of the longitudinal walls of the border may comprise a recess inwhich the connecting tenninal is placed.

Preferably, one of the transverse walls of the border comprises on itsexternal face a protruding housing the walls of which extendsubstantially perpendicular to the transverse wall, the lead frameincluding at least one electrical connector placed in this housing, thisconnector allowing the lead frame to be connected to the system forsupplying electrical power.

The external face is here the face directed toward the exterior of thelead frame.

Another subject of the invention is a light-emitting assembly, whereinit comprises:

-   -   a system for electrically connecting at least one light source        to a system for supplying electrical power according to the        invention;    -   at least one light source; and    -   a second means for dissipating heat allowing the heat generated        by the light source to be dissipated, this second means for        dissipating heat being disconnected from the lead frame.

The first means for dissipating heat is advantageously able to dissipatemore heat than the second means for dissipating heat.

Preferably, the light source is a light-emitting diode (LED), thislight-emitting diode possibly being single- or multi-die diodes.

The second means for dissipating heat is preferably a holder of thelight source.

The second means for dissipating heat advantageously consists of asubstrate on which the light source is mounted. This holder may forexample be made of metal or of ceramic.

According to one variant embodiment of the invention, the second meansfor dissipating heat comprises a radiator placed near or in contact withthe light source, this second means for dissipating heat possibly beingassociated with a heat pipe joined at one of its ends to the lead frameand at its other end to the radiator. The use of a heat pipe is madepossible by virtue of the arrangement of the light source away from thelead frame, which allows bulk at the lead-frame level to be decreased.

According to one variant embodiment of the invention, the second meansfor dissipating heat includes a radiator and a metal holder of theaforementioned type.

Another subject of the present invention is also a lighting and/orsignaling device for an automotive vehicle, wherein it includes alight-emitting assembly according to the invention.

These and other objects and advantages of the invention will be apparentfrom the following description, the accompanying drawings and theappended claims.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

Other features and advantages of the present invention will becomeapparent in light of the following examples and appended figures, theexamples and figures being given by way of completely nonlimitingillustration.

FIG. 1 is a schematic perspective representation of the lead frame ofthe system according to invention; and

FIG. 2 is a schematic perspective representation of the lead frame ofthe system according to the invention to which a light source isconnected.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

For the sake of clarity, only elements essential to the comprehension ofthe invention have been shown schematically and not to scale.

Such as shown in FIG. 1, the electrically connecting system 1 accordingto the invention includes a lead frame 3 able to be electricallyconnected to a system for supplying electrical power (not shown) such asthe electrical circuit of a vehicle.

The lead frame 3 takes substantially the form of a tray comprising:

-   -   a printed circuit board 7 to which electronic components may be        connected; and    -   a border including:        -   two substantially parallel longitudinal walls 8, 8′, one of            these longitudinal walls 8 comprising a recess 9; and        -   two substantially parallel transverse walls 10, 10′ that            each connect the two longitudinal walls 8, 8′, one of these            transverse walls 10 comprising on its external face a            protruding housing 11 the walls of which extend            substantially perpendicular to the transverse wall 10, this            housing 11 including:    -   two substantially parallel longitudinal walls 12, 12′; and    -   two substantially parallel transverse walls 13, 13′ each        connecting the longitudinal walls 12, 12′.

The board 7 is for example a PCB (printed circuit board) that includesat least one conductive layer ovennolded with an electrically insulatingmaterial, for example an epoxy resin or fiberglass.

This board 7 comprises electrical tracks 14 allowing electrical currentto be transported, these electrical tracks 14 being produced bysubjecting the conductive layer of the board 7 to a stamping process.

The lead frame 3 includes electronic components that are generallyconnected to the board 7 by laser soldering, these electronic componentsextending, according to the orientation of FIG. 1, above the board 7.

The end of the connecting pins of the electronic components pass throughthe board 7, thereby allowing visual inspection of the quality of thesolder joints formed on these ends to be carried out by means of opticaldevices.

The lead frame 3 includes at least one electrical connector 15 placed inthe housing 11, this connector 15 being connected to at least one of theelectrical tracks 14. The connector 15 allows the lead frame 3 to beconnected to the system 1 for supplying electrical power. The electricalconnector 15 may, for example, be a connecting pad able to allow thesystem for supplying electrical power to be connected by application ofthe wire bonding technique.

The lead frame 3 also comprises at least one connecting terminal 4placed in the recess 9, this connecting terminal 4 being able tointeract with a connecting means 5, to electrically connect a lightsource 2 to the lead frame 3.

The connecting terminal 4 is a connecting pad able to allow the lightsource 2 to be connected by application of the wire bonding technique,the connecting means 5 being an electrically conductive wire.

In addition, the lead frame 3 includes a first means 6 for dissipatingheat allowing the heat generated by the lead frame 3 to be dissipated,this first means 6 for dissipating heat consisting of a resistivecircuit.

Furthermore, the lead frame 3 comprises:

-   -   means allowing the AC voltage of the current delivered by the        system for supplying electrical power to be converted into a DC        voltage applied to the connecting terminal 4 of the lead frame        3; and    -   a switching circuit that controls that voltage of the current        which is applied to the connecting terminal 4, the switching        circuit possibly for example ensuring that this voltage is        comprised in a defined interval.

In this way, the lead frame 3 allows the voltage of the currentdelivered by the system for supplying electrical power to be convertedand adapted in order to apply to the connecting terminal 4 a suitablevoltage.

According to one variant embodiment of the invention, the space boundedby the border of the lead frame 3 may be filled with a liquefied plasticproduct (using a potting process).

Such as is shown in FIG. 2, a lighting assembly 16 according to theinvention comprises:

-   -   a system 1 for electrically connecting at least one light source        2 to a system for supplying electrical power as described above;    -   at least one light source 2; and    -   second means 17 for dissipating heat allowing the heat generated        by the light source 2 to be dissipated, this second means 17 for        dissipating heat being disconnected from the lead frame 3.

Thus, each connecting means 5 connects one connecting te niinal 4 to aconductive pad 18 that is connected to at least one light source 2.

The light source 2 and the conductive pads 18 are placed on the secondmeans 17 for dissipating heat, consisting in the present case of a metalholder.

The light source 2 is a light-emitting diode the emissive portion ofwhich is composed of a semiconductor chip or of a plurality ofsemiconductor chips, in the first case the diode is what is called amono-chip diode and in the second case the diode is what is called amulti-chip diode.

Placing the light source 2 away from the lead frame 3 makes it possibleto simplify the structure of the lead frame 3, which no longer requiresmeans for specifically dissipating the heat emitted by the light source2.

While the system, apparatus, process and method herein describedconstitute preferred embodiments of this invention, it is to beunderstood that the invention is not limited to this precise system,apparatus, process and method, and that changes may be made thereinwithout departing from the scope of the invention which is defined inthe appended claims.

1. A connecting system for electrically connecting at least one lightsource to a system for supplying electrical power of a motor vehicle,said connecting system comprising: a circuit board configured to beelectrically connected to said system for supplying electrical power ofa motor vehicle; at least one connecting terminal attached to thecircuit board; a light source holder spaced apart from the circuitboard; a light source of a vehicle light device, said light source beingmounted on the light source holder; and at least one conductive bridgespanning from said at least one connecting terminal to said light sourceholder such that said at least one connecting telininal is electricallyconnected to said light source, thereby allowing said light source to bespaced apart from said circuit board.
 2. The connecting system asclaimed in claim 1, wherein said circuit board includes a first heatdissipater to dissipate heat generated by said circuit board.
 3. Theconnecting system as claimed in claim 2, wherein said first heatdissipater is a resistive circuit.
 4. The connecting system as claimedin claim 1, wherein said circuit board includes a converter configuredto convert an AC voltage delivered by said system for supplyingelectrical power of a motor vehicle to a DC voltage applied to said atleast one connecting terminal.
 5. The connecting system as claimed inclaim 1, wherein said circuit board includes a control circuit thatcontrols said DC voltage applied to said at least one connectingterminal.
 6. The connecting system as claimed in claim 1, wherein saidat least one connecting terminal is a connecting pad configured to allowsaid at light source to be connected to the light source mount byapplication of a wire bonding technique.
 7. The connecting system asclaimed in claim 1, wherein said at least one conductive bridge is anelectrically conductive wire.
 8. The connecting system as claimed inclaim 7, wherein said electrically conductive wire is a non-insulatedwire.
 9. The connecting system as claimed in claim 7 wherein said atleast one conductive bridge is a wire-bond wire.
 10. The connectingsystem as claimed in claim 1, wherein said circuit board comprises aprinted circuit board to which electronic components may be connected.11. A light-emitting assembly, wherein said assembly comprises: aconnecting system for electrically connecting said at least one lightsource to said system for supplying electrical power according to claim2; and a second heat dissipater to dissipate heat generated by said atleast one light source, said second heat dissipater being disconnectedfrom said circuit board.
 12. The assembly as claimed in claim 11,wherein said at least one light source is a light-emitting diode. 13.The assembly as claimed in claim 11, wherein said second heat dissipateris said light source holder of said at least one light source.
 14. Alighting and/or signaling device for an automotive vehicle, wherein saiddevice includes said light-emitting assembly according to claim
 11. 15.The connecting system as claimed in claim 1, further comprising anelectrical connector attached to the circuit board and separated fromthe at least one connecting terminal.
 16. The connecting system asclaimed in claim 15, wherein said circuit board has a substantiallyrectangular shape, said electrical connector and said at least oneconnecting terminal being attached to the circuit board at differentside of the rectangular shape.
 17. The connecting system as claimed inclaim 1, wherein said light source holder comprises at least oneconductive pad provided on the surface of the light source holder andelectrically connected to said light source.
 18. The connecting systemas claimed in claim 17, wherein said conductive bridge is attached tosaid conductive pad.
 19. The connecting system as claimed in claim 18,wherein said conductive bridge is attached to said conductive pad bysolder.
 20. The connecting system as claimed in claim 1, wherein saidlight source holder is a metal holder.